Herbicidal method



United States Patent 3,403,994 HERBICIDAL METHOD John F. Olin, Ballwin, Mo., assignor to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Continuation of application Ser. No.

568,973, July 29, 1966, which is a continuation of application Ser. No. 416,664, Oct. 15, 1964, which in turn is a division of application Ser. No. 134,166, Aug. 28, 1961, both now abandoned. This application Nov. 7, 1967, Ser. No. 681,298

9 Claims. (Cl. 71-118) ABSTRACT OF THE DISCLOSURE Plant growth is effectively controlled with a compound of the formula wherein R is selected from the group consisting of primary alkyl and secondary alkyl of not morethan 4 carbon atoms, R is selected from the group consisting of primary alkyl and secondary alkyl of at least 2 and not more than 4 carbon atoms, and X is a halo-gen atom selected from the group consisting of chlorine, bromine and iodine.

This application is a continuation of applica tion Ser. No. 568,973, filed July 29, 1966, which in turn is a continuation of application Ser. No. 416,664, filed Oct 15, 1964, both now abandoned, which in turn is a division of application Ser. No. 134,166, filed Aug. 28, 1961 and now abandoned.

This invention relates to the control of plant systems, including germinating seeds, emerging seedl ngs, and fully developed plants. In one aspect, this invention relates to valuable herbicidal compositions. In another aspect, this invention relates to methods for destroying undes rable plant vegetation without substantiallyaffecting desirable plant vegetation. In another aspect, this invention relates to methods for preventing the germination of seeds of undesirable plants and for preventing the growth of emerging seedlings of said plants. In another aspect, this invention relates to certain solely ortho di-substituted u-haloacetanilides as new compounds.

In recent years, the use of chemicals for affecting plant systems has found wide-spread acceptance among agrieulturalists. For example, chemical compositions have been applied to fully developed vegetation to destroy the same in either a selective or non-selective manner. It is relatively easy to destroy the aerial portion of developed vegetation because the vegetation is brought into d rect contact with the herbicide composition; however, it is sometimes more difficult to achieve a lethal alfect on germinating seeds lying in the soil and seedlings emerging from the soil. Destruction of germinating seeds and emerging seedlings is important in preventing regrowth from the plants after the herbicide composition has either been washed away by rainfall or dissipated by other actions. Unfortunately, it is usually necessary to use an excessive amount of the herbicidal composition in order to affect the germinating seeds and emerging seedlings and thereby achieve long-lasting plant control. The extended control of plant life during the growth of desirable plants is very often involved in preventing the growth of certain undesirable grasses and weeds, such as crab grass and foxtail. Obviously, a more bountiful growth of desirable ice grasses and crop plants will result if growth of these undesirable weeds and grasses is prevented before the soil soil is depleted of moisture and nutrients. w

Very useful herbicidal compositions containing certain nuclear-substituted and nitrogen-substituted a-haloacetanilides are disclosed and claimed in US. Patent 2,863,752, issued to Hamm and Speziale. They discovered that the u-haloacetanilides required an alkyl substituent of up to 6 carbon atoms onthe amide nitrogen atom and a single alkyl substitutent of up to 4 carbon atoms on the aromatic ring in order to produce herbicidal activity. Even though these a-haloacetanilides of Hamm and Speziale are efiective herbicides, it is desirable in mans continued battle with undesirable plant life to improve the effectiveness of these herbicidal compositions.

I have now discovered, much to my surprise, that the unit activity of the u-haloacetanilides is increased and the plant spectrum widened at low rates of application by substituting certain alkyl substituents on the aromatic ring in each of the ortho positions with respect to the amide nitrogen atom, none of said substituents being a tertiary alkyl group, and not substituting any other substituents on either the aromatic ring or the amide nitrogen atom.

An object of this invention is to provide novel herbicidal compositions containing as an essential ingredient an a-haloacetanilide having certain alkyl substituents in only both ortho positions with respect to the amide nitrogen atom and none of said substituents being a tertiary alkyl group.

Another object of this invention is to provide novel herbicidal compositions having a high unit activity and a wide plant spectrum at low rates of application.

Another object of this invention is to provide novel herbicidal compositions useful for soil sterilization at low rates of application.

Another object of this invention is to provide novel herbicidal compositions which exhibit selectivity in affecting certain undesirable plant systems without affecting desirable plant systems.

Another object of this invention is to provide methods for the suppression and control of vegetation.

Another object of this invention is to provide methods for the suppression and control of undesirable vegetation growing inter-mingled with desirable vegetation.

Another object of this invention is to provide methods for preventing the germination of seeds of undesirable plants and for preventing the growth of undesirable emerging seedlings in soil which is planted with seeds of desirable vegetation.

Another object of this invention is to provide as new compounds certain a-haloacetanilides having only ortho alkyl substituents and none of said ortho substituents being a tertiary alkyl group.

Other aspects, objects, and advantages of this invention will be apparent from a consideration of the accompanying disclosure and the appended claims.

According to the present invention, there are provided herbicidal concentrate compositions comprising a herbicide adjuvant and an a-haloacetanilide of the formula wherein R is selected from the group consisting of primary alkyl and secondary alkyl radicals having 1 to 4 carbon atoms, R is selected from the group consisting of primary alkyl and secondary alkyl radicals having 2 to 4 carbon atoms, and X is a halogen atom selected from the group consisting of chlorine, bromine, and iodine.

Also, according to the present invention, there are provided herbicidal compositions comprising a carrier, a herbicide adjuvant and a toxic or growth-inhibiting amount of an a-haloacetanilide of the formula as described above.

Also, according to the present invention, there are provided methods for affecting plant systems, including fully developed vegetation as well as germinating seeds and emerging plant seedlings, in a manner to destroy said vegetation and to prevent the growth of said seeds and said emerging seedlings by the application of a toxic or growth-inhibiting amount of an a-haloacetauilide of the formula as described above.

Further, according to the present invention, there are provided, as new compounds, u-haloacetanilides of the formula as described above.

The a-haloacetanilides of this invention have substituents substituted on the aromatic ring in only the ortho positions with respect to the amide nitrogen atom. There are no substituents on either the amide nitrogen atom or the meta or para positions on the aromatic ring. One of the ortho substituents, R in the formula above, is either a primary or a secondary alkyl radical having at least 1 carbon atom and not more than 4 carbon atoms. This alkyl radical may be either straight chain or branched chain in configuration but there can be no tertiary alkyl group. Examples of some suitable alkyl radicals include: methyl, ethyl, n-propyl, isopropyl, n-butyl, and sec-butyl.

The other ortho substituent, R in the formula above, is either a primary or a secondary alkyl radical. This alkyl radical may have also either a straight chain or a branched chain configuration, so long as there is no tertiary alkyl group. This alkyl radical has from 2 to 4 carbon atoms. Examples of suitable alkyl radicals include ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, and sec-butyl.

The halogen substituent on the tat-carbon atom of the haloacetanilide, identified by X in the formula above, may be either a chlorine, bromine, or iodine atom.

The a-haloacetanilides of this invention may in general be prepared by haloacetylation of suitable ortho-substituted aromatic amines, which may be prepared for example, by the process disclosed in application S.N. 824,455 filed July 2, 1959, now abandoned, from a primary aromatic amine and a branch-chain olefin. The haloacetylating agent is preferably either a haloacetic anhydride, such as chloroacetic anhydride, or a haloacetyl halide, such as chloroacetyl chloride, bromoacetyl bromide, or the like.

The haloacetylation reaction is preferably conducted in the presence of a suitable liquid reaction medium. The liquid reaction medium must be anhydrous if the acetylating agent is a haloacetic anhydride; however, either anhydrous reaction mediums or mediums containing water can be used with haloacetyl halide acetylating agents. Examples of some suitable reaction mediums for use with either acetylating agent include benzene, diethyl ether, hexane, methylethyl ketone, chlorobenzene, toluene, chloroform, and the xylenes. Since an acid or hydrogen halide is eliminated in the haloacetylation reaction, it is also desirable to have an acid acceptor present in the reaction zone to neutralize the acid formed. Suitable acid acceptors for anhydrous solvent systems, include the ortho-substituted aromatic amine reactants, which may be present in the reaction zone in an amount greater than that required for the acetylation, tertiary amines, and pyridine. Acid acceptors in aqueous solvent systems include alkali or alkaline earth hydroxides and alkali or alkaline earth metal carbonates or bicarbonates.

The haloacetylation reaction is generally carried out at a temperature which is below room temperature, preferably in the range of from 0 C. to C. It is not usually desirable to carry out the reaction at a temperature above room temperature because hydrolysis of the haloacetyl halide takes place and the reaction rate is excessively high. It is generally preferable to carry out the reaction at atmospheric pressure although sub-atmospheric pressure and super-atmospheric pressure can be used. Although the haloacetylation reaction can be carried out using stoichiometric amounts of reactants, it is usually preferable to use from 2 to 5% of an excess of the acetylating agent. The acetanilide products may be separated from the reaction mixture by methods well known to those skilled in the art, such as by distillation or by fractional crystallization from the reaction medium or from solvents in case the desired product is a soluble substance.

The advantages, desirability and usefulness of the present invention are illustrated by the following examples.

Example 1 In this example, 2-chloro-2,6-diethylacetanilide was prepared from 2,6-diethylaniline and chloroacetyl chloride. Into a 1-liter reaction flask were placed 45 g. (0.3 mole) of 2,6-diethylani1ine, 30 g. of sodium bicarbonate, 100 ml. of Water, and 300 g. of ice. Thereafter, 35 g. (0.31 mole) of chloroacetyl chloride in 100 ml. of benzene was added dropwise over a 30-minute period with stirring while maintaining the temperature at approximately 0 C. During the addition of the chloroacetyl chloride, an additional 150ml. of benzene was added to the reaction flask. Upon completion of the addition of the chloroacetyl chloride, the reaction mixture was stirred for an additional 15 minutes. At the end of this time, the soiid material in the reaction mixture was separated by filtration, washed with water, and crystallized from methanol to obtain 45.5 g. of the 2-chloro-2,6-diethylacetanilide which is a colorless solid having a melting point of 133.4134 C. Analysis of the product was found to be 15.72% chlorine as compared with the calculated value of 15.78% chlorine.

Example 2 In this example, 2-chloro-2',6'-di-isopropy1acetanilide was prepared from 2,6-diisopropylaniline and chloroacetic anhydride. Into a reaction flask were placed 49 g. (0.28 mole) of 2,6-diisopropylaniline, 32 g. of sodium bicarbonate, ml. of water, and 300 g. of ice. Thereafter 35 g. of chloroacetyl chloride in 100 ml. of benzene was added slowly over a 30-minute period with stirring while maintaining the temperature at 1 C. During the addition of the chloroacetyl chloride, 100 ml. of benzene was added to the reaction flask. Upon completion of the addition of the chloroacetyl chloride, the reaction mixture was stirred for an additional 15 minutes. At the end of this time, the solvents were removed under vacuum. The solid material present in the reaction mixture was removed by filtration, washed with water, and crystallized from 80% methanol to obtain 45.5 g. of 2-chloro-2,6'- di-isopropylacetanilide which is a colorless solid having a melting point of 151.4151.9 C. Analysis of the product was found to be 14.1% chlorine as compared with the calculated value of 13.97% chlorine.

Example 3 In this example, 2-chloro-2-methyl-6'-isopropylacetanilide was prepared by reacting 149 g. (1 mole) of 2'isopropyl-6methylaniline dissolved in 300 g. of benzene with 158 g. (1.05 moles) of chloroacetic anhydri-de in 158 g. of chloroform. Although a slow exothermic reaction took place, the reaction mixture was heated on a hot plate with boiling for a period of 2 hours. At the end of this time, 300 ml. of water was added to the reaction mixture and the solvents removed by distillation. The solid material remaining in the reaction mixture was separated by filtration and washed with 300 ml. of water. The filter cake was dissolved in 300 ml. of hot methanol and cooled to effect crystallization of the product. From the crystallization there was obtained 184 g. of the 2-chloro-2'-methyl-6-isopropylacetanilide which is a white solid material having a melting point of 116116.5 C. Analysis of this product was found to be 15.95% chlorme as compared with the calculated value of 15.78% chlorine.

Example 4 In this example, 2-bromo-2,6-diethylacetanilide was prepared by reacting 40 g. of N-tert-butyl-2-ethylaniline dissolved in 130 ml. of heptane with 20.5 g. of bromoacetyl bromide in 25 ml. of hexane while maintaining the temperature in the range of 8-10" C. The bromoacety] bromide was added to the N-tert-butyl-2-ethylaniline over a period of about minutes and the reaction mixture was then stirred an additional 10 minutes. At the end of this time, 100 ml. of hot water was added to the reaction mixture. The oil layer formed was separated, washed with dilute hydrochloric acid, and washed with water. Evaporation then followed to remove the solvents. Crystallization was effected by cooling to obtain 4.5 g. of the 2-bromo-2',6'-diethylacetanilide which is a white solid material having a melting point of 113113.5 C.

Example 5 In this example, the pre-emergent herbicidal ratings of some of the ortho-substituted a-haloacetanilides of this invention were determined in greenhouse tests in which a specific number of seeds of 12 different plants, each representing a principal botanical type, were planted in greenhouse flats. A good grade of top soil was placed in either 9 /2" x 5%" x 2%" or 9 x 13" x 2" aluminum pans and compacted to a depth of 73 inch from the top of the pan. On top of the soil were placed five seeds of each of radish, morning glory, and tomato; 10 seeds of each of sugar beet, sorghum, and brome grass; seeds of each of wild buckwheat, giant foxtail, rye grass, and wild oat; approximately 20 to 30 (a volume measure) of each of pigweed and crab grass, and either 2 or 3 seeds of soybean. Two different type plantings were made; one wherein the herbicidal composition was applied to the surface of the soil and the other wherein the composition was admixed with or incorporated in the top layer of soil. In the surface-application plantings, the seeds were arranged with 3 soybean seeds across the center of the large aluminum pan, the monocotyledon or grass seeds scattered randomly over one-third of the soil surface, and the dicotyledon or broadleaf seeds scattered randomly over the remaining one-third of the soil surface at the other end of the pan. The seeds were then covered with inch of prepared soil mixture and the pan leveled. In the soil-incorporation plantings, 450 g. of prepared soil mixture was blended with the herbicide composition in a separate mixing container for covering the seeds which were planted in the smaller of the two aluminum pans. The seeds in this planting were arranged with a soybean seed planted in diagonal corners and the monocotyledon seeds and the dicotyledon seeds each scattered randomly over one-half of the soil surface. The herbicideincorporated soil mixture was used to cover the seeds. The herbicide composition was applied in the surfaceapplication plantings prior to the watering of the seeds. This application of the herbicide composition was made by spraying the surface of the soil with an acetone solution containing a sufficient quantity of the candidate chemical to obtain the desired rate per acre on the soil surface. The watering of the seeds in both type plantings was accomplished by placing the aluminum pans in a sand bench having /2-inch depth of water thereon and permitting the soil in the pans to absorb moisture through the perforated bottom of the pans.

The planted pans were thereafter placed on a wet sand bench in a greenhouse and maintained there for 14 days under ordinary conditions of sunlight and Watering. At the end of this time, the plants were observed and the results recorded by counting the number of plants of each species which germinated and grew. The herbicidal rating was obtained by means of a fixed scale based on the average percent germination of each seed lot. The herbicidal ratings are defined as follows:

GNo phytotoxicity 1Slight phytotoxicity 2Moderate phytotoxicity 3Severe phytotoxicity The pre-emergent herbicidal activity of some of the ortho-substituted a-haloacetanilides of this invention are recorded in Table I for various application rates of the a-haloacetanilide in both surface and soil-incorporated applications. In Table I, the various seeds are represented by letters as follows:

A-General grass BGeneral broadleaf C-Morning glory DWild oats E-Brome grass FRye grass GRadish H--Sugar beet IFoxtail I-Crab grass KPigweed LSoybean M-Wild buckwheat N-Tomato O-Sorghum Individual injury ratings for each plant type are reported in Table I. In addition, the total injury rating for all grass plants and the total injury rating for all broadleaf plants are also reported in Table I. For grasses, the maximum total is 18 for the 6 grass plants at ratings of 3. For broadleafs, the maximum total is 21 for the 7 broadleaf plants at ratings of 3.

The data in Table I illustrate the general herbicidal activity as well as the selective herbicidal activity of some of the ortho di-substituted a-haloacetanilides of this invention. It wiil be noted that haloacetanili-des substituted with an alkyl group of 14 carbon atoms ortho to the amide nitrogen atom and another alkyl group of 2-4 carbon atoms also substituted ortho to the amide nitrogen atom demonstrate very outstanding general herbicidal activity at low rates of application. Thus, these 06-11310- acetanilides are particularly useful in soil sterilization applications. It will also be noted from the data in Table I that unusual grass specificity can be obtained at lower TABLE I.-PRE-EMERGENCE HERBICIDAL ACTIVITY OF THE ORTHO DI-SUBSTITUTED oc-HALOACETANILIDES Rate, Plant type Total injury rating Compound lb./acre Comments A B C D E F G H I J K L M N 0 Grass Broadleaf 2-e11loro-2',6-diethylacetanilide 25 3 3 3 3 3 3 1 2 3 3 3 2 2 3 3 18 16 5 3 2 3 3 3 3 0 2 3 3 3 1 2 3 18 1 11 I 1 3 2 2 3 2 3 0 2 3 3 3 2 1 3 17 10 2-chl0ro-2,6-d1-1sopropylacetan1l1de 25 3 1 1 3 3 3 1 2 3 3 3 0 0 2 3 18 19 5 3 1 2 3 3 3 0 1 3 3 3 1 1 3 18 8 1 3 1 0 2 3 3 0 2 3 3 3 1 3 3 17 1 9 a 0.15 2 0 0 0 0 3 0 0 2 3 3 1 0 2 10 4 2-chloro-2-rnethyl-6-1sopropylacetanilrde. 5 3 3 3 1 3 3 2 3 3 3 3 1 3 2 15 17 2-bromo-2,6 -diethylacetanilide 5 2 0 0 0 2 2 0 1 3 3 3 0 0 0 2 14 4 3 Incorporated in sot levels of application. Such grass specificity is achieved at extremely low application rates, for example, at rates as low as 0.15 lb. per acre with 2-chloro-2',6-di-isopropylacetanilide so that very economical treatment is possible. The three botanical types or genera of grasses effectively controlled by the ortho di-substituted u-haloacetanilides of this invention embrace a large number of undesirable plants, or weeds, frequently found in vegetable crops. But these a-haloacetanilides are not limited to removing grasses from broadleaf plants, since the selective action is such that certain genera of grasses can be removed from corn, which is also a genus of grass. These a-haloacetanilides are also effective in killing nut grass, i.e., Cyperus rotundus and Cyperus esculentus.

Example 6 In this example, the lack of herbicidal activity of closely related compounds which do not have the structure of the ortho (ii-substituted a-hal'oacetanilides of this invention is demonstrated. Pre-emergent greenhouse tests were used in this example and the planting of the seeds was accomplished in the same manner as described in Example 5. The data obtained are reported in Table II wherein the identification of the seeds is the same as that in the previ ous example and the herbicidal ratings given also have the same definition.

The first comparison in Table II shows the critical nature of the alkyl substituents substituted in the ortho positions on the aromatic ring. Surprisingly, 2-chloro-2',6- diethylacetanilide, an acetanilide of this invention, has very high herbicidal activity at an application rate of 1 lb./ acre but 2-chloro-2',6-dimethylacetanilide, having methyl groups instead of ethyl groups substituted on the aromatic ring, has no herbicidal activity at the same rate of application.

In the last comparison reported in Table II, one ethyl group was removed from a 2-bromo-2,6'-diethylacetanilide and a tert-butyl group substituted on the amide nitrogen atom. Nevertheless, the herbicidal activity of the resulting compound, 2 bromo-N-tert-butyl-2'-ethylacetanilide, was very poor.

The data in this example very clearly demonstrate the critical effect on herbicidal activity of not only the nature of the alkyl groups substituted on the aromatic ring but also the necessity of two such alkyl groups. In order to have very high unit activities and wide plant spectrums, the u-haloacetanilide must be one which has two alkyl groups substituted in the ortho positions with respect to the amide nitrogen atom; one alkyl group having at least two carbon atoms and each alkyl group free of the tertiary configuration. 7

Example 7 In this example, the contact herbicidal activity of some of the a-haloacetanilides of this invention was determined in greenhouse tests. The a-haloacetanilide to be tested was applied in spray .form to 21-day old specimens of the same grasses and broadleaf plants as used in the preemergent tests described in Example 5. The same number of seeds of the same plants used in Example were planted in the 9 /2" x 5 /21" x 2%" aluminum pans ar- TABLE IL-GOMPARISON OF PRE-EMERGENCE HERBICIDAL ACTIVITY OF VARIOUS a-HALOACE'IANILIDES c d Plant type Total injury rating ompoun Comments A B C D E F G II I J K L M N 0 Grass Broadleaf Y 2-0111010-2' 6-diethylacetanilide 3 2 2 3 2 3 0 2 3 3 3 2 1 3 17 1 10 At 1 lb./acre. 2-chloro-2 ,6-dimethylacetanilide 0 0 0 0 0 0 O 0 0 0 0 0 O 0 0 0 0 D0, 2-chloro-2-mcthyl-6-is0propylacetanilids. 3 3 3 1 3 3 2 3 3 3 3 1 2 3 2 17 At 5 lb./acre. 2-chloro-2-isopropylacctanilide t 1 0 0 0 3 0 0 0 2 3 2 0 0 0 0 8 2 At 6 lb./acre. 2-chloro-2 fi diethylacetanilide 3 2 2 3 2 3 0 2 3 3 3 2 0.. l 3 17 1 10 At 1 lb./acre. 2-chloro-2 -ethylaeetauilide 0 0 0 0 0 0 0 O 1 0 2 0 0 1 0 1 3 D 2-chloro2,6-di-isopropylacetan1 3 1 2 3 3 3 O 1 3 3 3 1 1 3 18 1 8 At 5 lb./acre. 2chlor0-2-isopropylacetanilide 1 0 0 0 3 O 0 0 2 3 2 0 O 0 0 8 2 D0. 2chloro-2,6-diisopropylacetanilide. 3 1 1 3 3 3 1 2 3 3 3 0 0 2 3 18 9 At 1b./acre. 2-,6-di-tert-butyl-2-chl0roacetanilide. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O 0 D 2-bromo-2,6-diethylacetanilide 2 0 0 0 2 2 0 1 3 3 3 0 0 0 2 14 4 At 5 lb./acre. 2-br0m0 N-tert-butyl-2-ethylacetauilide 1 0 0 1 0 1 0 O 2 1 1 0 0 0 l 6 1 D 1 One species missing.

The second comparison in Table II shows the detrimental effect on herbicidal activity resulting from the removal of one of the alkyl substituents from the aromatic ring of the acetanilide. Thus, the herbicidal activity is very severely reduced it one of two dissimilar alkyl groups is removed from the aromatic ring; that is, the removal of the methyl group from 2-chloro-2'-methyl-6'isopropylacetanilide. Also, the herbicidal activity is severely reduced if one of similar alkyl groups is removed such as removal of an ethyl group from 2-chloro-2,6-diethylacetanilide. Furthermore, the detrimental effect on herbicidal activity is the same even if the alkyl groups are branchchain as in the removal of an isopropyl group from 2- chloro-Z,6-di-isopropylacetanilide. The herbicidal activity in each of these three examples is very low for the mono-substituted acetanilides as compared with the corresponding di-substituted acetanilides.

The next comparison demonstrates that the secondary alkyl groups cannot be changed to tertiary alkyl groups without destroying the herbicidal activity of the acetanilides. Thus, 2-chloro-2',6'-di-isopropylacetanilide, which is substituted with two isopropyl groups, has very high herbicidal activity whereas 2,6'-di-tert-butyl-2-chloroacetanilide, which is substituted with two tertiary alkyl groups, has very low herbicidal activity.

TABLE III-CONTACT HERBICIDAL ACTIVITY OF CER- TAIN ORTHOSUBSTITUTED a-HALOACETANILIIDES C omp ound General General grass broadleat 2-chloro-2 ,G dict hylaeetauilide 0 1 2-chloro-2 ,6-d1-isopropy1acctanilide" 1 1 2-cl1loro-2-methyl2-isopropylacetanilide 2 2 2-brorno-2,6-dlethylacetanilide 0 1 v The herbicidal compositions of this invention are either particulate solid (i.e., dusts) or liquid concentrate compositions comprising the active ingredient and either a particulate solid 'or liquid herbicidal adjuvant whichare formulation aids or conditioning agents ,permittingthe concentrate composition to be readily mixed a lsuitable solid or liquid carrier in the field for application of the active ingredient on soil or plant surfaces in a toxic concentration in a form which enables prompt assimilation by the germinating seeds, emerging seedlings, or full grown plants. Thus, the herbicidal compositions of this invention include not only the concentrate compositions comprising the active ingredient and the herbicidal adjuvant but also herbicidal toxicantcompositions applied in the field comprising the concentrate composition (i.e., active ingredient plus herbicidal adjuvant) and the carner. I 1

As demonstrated in the examples above, quite different effects can be obtained by modifying the method of use of the herbicidal composition of this invention. Thus, unusual grass specificity can be achieved at lower levels of application whereas at higher levels of application a more general herbicidal effect or soil sterilization takes place. Therefore, an essential part of this inventionis the formulation of the herbicidal composition so as to permit a uniform predetermined application of the composition to the plant environment to produce the desired effect.

Herbicidal adjuvants useful in preparing the concentrate compositions and, therefore, the herbicidal toxicant compositions applied to the soil or, plants, include particulate solid or liquid extending agents such as solvents or diluents within which the active ingredient is dissolved or suspended, wetting, or emulsifying agents which serve in'providing uniform dispersions or solutions of the active ingredient in the extending agents, and adhesive agents or spreading agents which improve the contact of the active ingredient with the soil or plant surfaces. All herbicidal compositions of this invention include at least one of the above types of herbicidal adjuvants and usually include an extending agent and a wetting or emulsifying agent because of the nature of the physical properties of the a-haloacetanilides of this invention.

In general, the a-haloacetanilides of this invention are insoluble in water and are not readily soluble in many organic solvents. Therefore, the choice of a liquid extending agent is somewhat limited if it is desired that the active ingredient be in solution in the extending agent. The active ingredient need not be dissolved in the extending agent but may merely be dispersed or suspended in the extending agent as a suspension or emulsion. Also, the a-haloacetanilides may first be, dissolved in a suitable organic solvent and the organic solution of the active ingredient then incorporated in water or an aqueous extending agent to form a heterogenous dispersion. Examples of some suitable organic solvents for use as extending agents include hexane, benzene, toluene, acetone, cyclohexanone, methylethylketone, isopropanol, butanediol, methanol, diacetone alcohol, xylene, dioxane, isopropyl ether, ethylene dichloride, tetrachloroethane, hydrogenated naphthalene, solvent naphtha, petroleum fractions (e.g., those boiling almost entirely under 400 F. at atmospheric pressure and having flash points above about 80 F., particularly kerosene), and the like. Where true solutions are desired, mixtures of organic solvents have been found to be useful, for example, 1:1 and 1:2

mixtures of xylene and cyclohexanone.

Solid extending agents in the form of particulate solids are very useful in the practice of the present invention because of the low solubility properties of the u-haloacetanilides of this invention. In using this type of extending agent, the active ingredient is either adsorbed or dispersed on or in the finely-divided solid material. Preferably the solid extending agents are not hygroscopic but are materials which render the composition permanently dry and free flowing. Suitable solid extending agents include the natural clays, such as china clays, the bentonites and the attapulgites; other minerals in natural state, such as talc, pyrophyllite, quartz, diatomaceous earth, fullers earth, chalk, rock phosphate, kaolin, kieselguhr, volcanic ash, salt, and sulfur; the chemically modified minerals, such as acid-washed bentonite, precipitated calcium phosphate, precipitated calcium carbonate, calcined magnesia, and colloidal silica; and other solid materials such as powdered cork, powdered wood, and powdered pecan or walnut shells. These materials are used in finely-divided form, at least in a size range of 20-40 mesh and preferably in much finer size.

The particulate solid concentrate compositions are applied to the soil by admixture at the time of application with a particulate solid carrier material. If desired, this concentrate composition can also be applied as a wettable powder using a liquid carrier material. When used by this method, a wetting agent or surface active agent is added to the concentrate composition in order to render the particulate solid extending agent wettable by water to obtain a stable aqueous dispersion or suspension suitable for use as a spray. Also, the extending agent applied as a wettable powder is used in very finely-divided form, preferably in a size as small as 100 mesh or smaller.

The surface active agent, that is the wetting, emulsifying, or dispersion agent, used in the herbicidal composition of this invention to serve in providing uniform dispersions of all formulation components of both liquid and dust types in both the concentrate compositions and the toxicant compositions applied, may be either anionic, cationic, or non-ionic types, including mixtures thereof. Suitable surface active agents are the organic surface active agents capable of lowering the surface tension of water and include the conventional soaps, such as the water-soluble salts of long-chain carboxylic acids; the amino soaps, such as the aminesalts of long-chain carboxylic acids; the sulfonated animal, vegetable, and mineral oils; quaternary salts of high molecular weight acids; rosin soaps, such as salts of abietic acid; sulfuric acid salts of high molecular weight organic compounds; algin soaps; ethylene oxide condensated with fatty acids, alkyl phenols and mercaptans; and other simple and polymeric compositions having both hydrophilic and hydrophobic functions. The herbicidal concentrate compositions of this invention ordinarily have the active ingredient and the surface active agent present in higher concentrations than the toxicant compositions applied in the field so that upon dilution with the liquid or solid carrier, compositions containing optimum proportions of active ingredient and surface active agent are prepared to obtain uniform distribution and to maintain the active ingredient in a form which enables the prompt assimilation by the plant.

The liquid concentrate compositions of this invention preferably comprise 5% to by weight of the active ingredient and the remainder the herbicidal adjuvant, which may be solely liquid extending agent or surface active agent (including adhesive agent), but preferably is a combination of liquid extending agent and surface agent. Preferably, the surface active agent comprises from 0.1% to 15% by weight of the total concentrate composition. The remainder of the composition is the liquid extending agent.

Use of the surface active agent is necessary in the formulation of liquid concentrate compositions in order to obtain a composition containing a sufficient concentfation of the difficultly soluble a-haloacetanilide in the liquid extending agent. However, the liquid extending agent must be selected not only on the basis of the amount of the a-haloacetanilide dissolved but also upon the basis of the solution temperature of the total composition. Thus, in some formulations, a particular combination of solvents gives a sufficiently low solvent temperature but the amount of the a-haloacetanilide dissolved or dispersed in the mixture is insufficient and a suitable surface active agent must be selected in order that more u-haloacetanilide can be dispersed in the composition. Preferably, the concentrate composition has a solution temperature below 0 C. although compositions having solution temperatures as high as 20 C. can be used.

The concentration of a-haloacetanilide in the particulate solid or dust concentrate composition of this invention may vary over wide ranges depending upon the nature of the solid extending agent and the intended use of the composition. Since the oc-haloacetanilides of this invention have very high toxicities and are applied at very low rates in order to obtain selectivity, the concentration of the active ingredient in the dust composition may be very low and may comprise as little as 1% or less by wt. of the total dust composition. By contrast, when the dust composition is to be used for soil sterilization, it may be desirable to have a very high concentration of active ingredient and for such use the active ingredient may comprise as much as 5% to 98% by wt. of the total composition. The remainder of the composition is the herbicidal adjuvant which is usually only the particulate solid extending agent. Thus, the surface active agent is not usually required in dust concentrate compositions although it can be used if desired. However, if the dust concentrate composition is to be applied as a wettable powder, surface active agent must be added to the concentrate composition and ordinarily the amount of surface active agent will be in the range of 0.1% to by wt. of the composition.

The carrier material, used for the uniform distribution of the a-haloacetanilide in a herbicidally effective amount to inhibit the growth of either all or selected plants, may be either a liquid or a particulate solid material. The liquid and solid extending agents used to prepare the concentrate composition may also be used as the carrier; however, the use of these materials as a carrier is often not economical. Therefore, water is the preferred liquid carrier, both for use with the liquid concentrate composition and the wettable powder concentrate. Suitable particulate solid carriers include the particulate extending agents noted above as well as the solid fertilizers such as ammonium nitrate, urea, and superphosphate, as well as other materials in which plant organisms may take root and grow, such as compost, manure, humus, sand and the like.

The liquid and dust concentrate compositions of this invention can also contain other additaments such as fertilizer and pesticides. Also, these additaments may be used as, or in combination with, the carrier materials.

The herbicidal compositions of this invention are applied to the plant systems in the conventional manner. Thus, the dust and liquid compositions may be applied to the foliage of growing plants by the use of powerdusters, broom and hand sprayers, and spray-dusters. The compositions can also be very suitably applied from airplanes as dust or spray because the herbicidal compositions of this invention are effective in very low dosages. In order to prevent growth of germinating seeds or emerging seedlings, the dust and liquid compositions are applied to the soil according to conventional methods, and, preferably, distributed in the soil to a depth of at least /2 inch below the soil surface. It is not absolutely necessary that the herbicidal compositions be admixed with the soil particles and these compositions can be applied merely by spraying or sprinkling onto the surface of the soil. The herbicidal compositions of this invention can also be applied by addition to irrigation water supplied to the field to be treated. This method of application permits the penetration of the compositions into the soil as the water is absorbed therein. Dust compositions sprinkled on the surface of the soil can be distributed below the surface of the soil by the usual discing, dragging, or mixing operations.

The application of a growth-inhibiting amount or toxic amount of the u-haloacetanilide to the plant system is essential in the practice of the present invention. The exact dosage to be app-lied is dependent not only upon the specific a-haloacetanilide but also upon the particular plant species to be controlled and the stage of growth thereof as well as the part of the plant to be contacted with the toxicant. In non-selective foliage treatments, the

herbicidal compositions of this invention are usually applied at a rate sufficient to obtain from 5 to 50 lbs. of ot-haloacetanilide per acre but lower or higher rates might be applied in some cases. In non-selective pre-emergent treatments, these herbicidal compositions are usually applied at a somewhat lower rate than in foliage treatments but at a rate which is ordinarily within the same general range; that is, at a rate in the range of l to 25 lbs. per acre. However, because of the unusually high unit activity possessed by the ot-haloacetanilides of this invention, soil sterilization is ordinarily accomplished at a rate of application in the range of 3 to 9 lbs. per acre. In selective pre emergent applications to the soil, a dosage of from 0.15 to 5 lbs. of active ingredient per acre is usually employed but lOWBI'Ol" higher rates may be necessary in some instances. It is believed that one skilled in the art can readily determine from this disclosure, including the examples, the optimum rate to be applied in any particular case.

Although the active ingredient in the herbicidal compositions of this invention is preferably an ortho di-substituted a-haloacetanilide as described in this specification, other a-haloacetanilides having other nuclear alkyl or halo substitution and/or no amide nitrogen substitution may also be present in the herbicidal compositions and contribute to the activity of the composition. However, the essential active ingredient of the herbicidal compositions of this invention is the ortho di-substituted a-haloacetanilide disclosed in this specification. Of course, one skilled in the art will understand that mixtures of various ortho di-substituted u-haloacetanilides can also be used.

Reasonable variation and modification of the invention as described are possible, the essence of which is that there have been provided (1) herbicidal concentrate compositions comprising a herbicidal adjuvant and, as an essential active ingredient, an ortho di-substituted u-haloacetanilide, (2) herbicidal toxicant com ositions comprising a herbicidal adjuvant, a carrier, and as an essential active ingredient, a toxic or growth-inhibiting amount of an ortho di-substituted a-haloacetanilide, (3) methods for suppression and control of undesirable vegetation, including full grown plants as Well as germinating seeds and emerging seedlings, by the application of an ortho di-substituted a-haloacetanilide thereto, and (4) certain ortho di-substituted a-haloacetanilides as new compounds.

I claim:

1. Method which comprises exposing a plant to a phytotoxic amount of a compound of the formula wherein R is selected from the group consisting of primary alkyl and secondary alkyl of not more than 4 carbon atoms, R is selected from the group consisting of primary alkyl and secondary alkyl of at least 2 and not more than 4 carbon atoms, and X is a halogen atom selected from the group consisting of chlorine, bromine and iodine.

2. Method of claim 1 wherein the plants are exposed pre-emergently by application of the compound to the soil.

3. Method of claim 1 wherein R and R are primary alkyl.

4. Method of claim 1 wherein R and R are secondary alkyl.

5. Method of claim 1 wherein R is primary alkyl and R is secondary alkyl.

6. Method of claim 1 wherein the compound is 2- chlor0-2,6'-diethylacetanilide.

7. Method of claim 1 wherein the chloro-2,6'-diisopropylacetanilide.

8. Method of claim 1 wherein the chloro-2-methyl-6'-isopropylacetanilide.

9. Method of claim 1 wherein the bromo-2,6-diethylacetanilide.

compound is 2- compound is 2- compound is 2- JAMES O. THOMAS, JR., Primary Examiner.

References Cited UNITED STATES PATENTS Hamm et a1. Martin. Litvan et a1. Fielding et a1. Waring.

Olin. 

